1. Field of the Invention
This invention generally relates to boats and, more specifically, to wake-modifying devices for boats.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Various types of power boats have been used for towing people for water sports, including those powered by outboard motors and inboard motors. Embodiments of a conventional power boat 10 having an inboard motor are shown in FIGS. 1-3 as having a hull 12, which extends along a longitudinal axis 14 of the boat from a bow 16 to a stern 18, and which extends outward from a center line 20 of the boat to a port side 22 and a starboard side 24. As described in more detail below, a center trim plate 26 is often pivotably mounted to the transom 28 at the center line 20 to adjust the trim of the boat.
Many power boats are designed to tow people with a specific water sport in mind, such as but not limited to water skiing, knee-boarding, wake boarding and wake surfing. The size and shape of desirable wakes varies for each sport and is also dependent on the skill and preference of the person performing the sport. For instance, it is often desirable to water ski and knee board on relatively flat wakes, whereas relatively larger wakes are generally desirable for wake boarding and wake surfing. Given such variances on desirable sizes and shapes of wakes for different water sports and preferences, achieving differing and optimal wake size and shape for each sport and skill-type on a given boat is very difficult.
For example, some power boats may be designed for producing relatively large wakes, and thus, may have a hull 12 with a deep V-shaped cross-section, as shown in FIG. 2. A hull with a deep V-shaped cross-section is described herein as exhibiting a deadrise angle (i.e., the angle α measured between the bottom surface of the hull and the horizontal from a point along the center line 20 to the port 22 or starboard 24 side) between approximately 15° and 45°. In some boats, the hull 12 may have a substantially consistent deadrise angle from the bow 16 to the stern 18. In other boats, the deadrise angle may gradually taper along the longitudinal axis 14 of the boat so as to produce a flat or semi-flat deadrise at the stern of the boat. In this type of power boat, it is desirable to get the front end of the hull 12 out of the water at a higher angle of attack as the boat accelerates to cut down on drag and allow the boat to go much faster. This causes the stern 18 of the boat to sit down lower into the water so that it effectively digs a trench along the path that it makes in the water, which in turn produces bigger wakes. For this reason, this type of boat is generally well-suited for water sports that benefit from large wakes, such as wake boarding and wake surfing.
To produce the relatively smaller wakes desirable for water skiing, a center trim plate 26 is often coupled to the transom 28 at the center line 20. The center trim plate 26 typically consists of a flat, substantially rectangular plate, and is typically coupled to the transom 28 via a hinge 30 and linear actuator 32, which moves the center trim plate 26 from a non-deployed position (out of the water) to a deployed position (into the water). As the boat moves through the water, the water flowing under the boat impinges on the deployed trim plate 26, creating an upward force on the trim plate which, in turn, raises the stern 18 to help plane the boat faster. When used for water skiing, the center trim plate 26 may be deployed to raise the stern 18 of the boat and minimize the wake.
In other types of power boats (FIGS. 1 and 3), the hull 12 may have a more shallow V-shape at the bow 16 that quickly merges into a flat or semi-flat bottom amidship and continues to the stern 18. A hull with a semi-flat bottom surface at the stern is described herein as having a deadrise angle (a) that ranges between approximately 5° and 12°. This flatter hull design runs with substantially greater surface area along the top of the water, and thus, produces higher drag. When run at speed, the flatter hull design does not lift with the high angle of attack characteristic of deep V-shaped hull boats, and thus, produces smaller wakes desired for water skiing. However, boats with these hull designs are generally unsuitable for wake boarding and wake surfing without further including some form of wake-modifying device.
The substantially flatter hull design shown in FIG. 3 also benefits from a center trim plate 26, which is coupled to the transom 28 at the center line 20 and made pivotable from a non-deployed position to a deployed position. As noted above, the center trim plate 26 is typically a flat, substantially rectangular plate. When the center trim plate 26 is actuated into the deployed position, the stern 18 of the boat is raised to produce smaller wakes desirable for water skiing. However, the substantially flatter hull design shown in FIG. 3 is generally unable to produce the larger wakes desired for wake boarding and wake surfing without utilizing some form of wake-modifying device. In order to produce larger wakes, additional trim tabs 34 and 36 are often mounted onto the transom 28; one on the port side and one on the starboard side of the center line 20. Similar to center trim plate 26, the port and starboard trim tabs 34 and 36 typically consist of a flat plate having one or more down-turned edges and/or one or more up-turned edges. In the example shown in FIG. 3, the port and starboard trim tabs 34 and 36 each comprise a trailing edge (i.e., the edge of the plate furthest from the transom) bent downward at some angle, and an outboard edge bent upward at some angle. When the port trim tab 34 is deployed to raise the port side of the boat, an increase in displacement on the starboard side of the boat increases the size of the starboard wake. Conversely, the starboard trim tab 36 may be deployed to increase the size of the port wake.
Even with the trim tabs described above, wake boarders and wake surfers desire larger wakes with improved wave shapes. For surfing in particular, wake surfers desire a wake with a large surfable area that extends substantially from the swim platform to the curl of the wake. As such, it is desirable to provide improved port and starboard trim tab designs (i.e., wake-modifying devices), which provide even greater wake shaping ability than is currently possible with conventional trim tab designs.